Retinitis Pigmentosa 22
For a phenotypic description and a discussion of genetic heterogeneity of retinitis pigmentosa, see 268000.
MappingFinckh et al. (1998) collected DNA samples from 20 large consanguineous Indian families in which autosomal recessive retinitis pigmentosa (arRP) segregated and that were suitable for homozygosity mapping of the disease locus. After excluding linkage to all known arRP loci, a genomewide scan was initiated. In 2 families, homozygosity mapping, haplotype analysis, and linkage data mapped the disease locus (RP22) in an approximately 16-cM region between D16S287 and D16S420 on the proximal short arm of chromosome 16. The location of RP22 was given as 16p12.3-p12.1.
Molecular GeneticsBy direct sequencing, Finckh et al. (1998) found no mutation in the CRYM gene (123740), which encodes mu crystallin and maps to the same region.